It makes sense that not only plagiarism services but also universities and other educational institutions have their definition and requirements for plagiarism and their level of plagiarism threshold for checking it.
Each teacher assesses their student's knowledge differently, and if 60% uniqueness is adequate for some, other teachers could demand 100% uniqueness. In any case, writing your work is always the best course of action.
Studying in an educational institution is primarily about acquiring knowledge. Even if you were lucky enough to have a sympathetic teacher, it does not mean you can copy someone else's material entirely.
The consequences of plagiarism in college will not the best for you, and therefore:
- Try to study as many different references as possible, but do not copy them.
- Quoting information is also acceptable but within reasonable limits.